


H2No!

by RicePoison



Category: H2O: Just Add Water, Miraculous Ladybug
Genre: F/M, mermaid au
Language: English
Status: In-Progress
Published: 2018-09-25
Updated: 2018-09-27
Packaged: 2019-07-17 13:45:45
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 3,554
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16096862
Author URL: https://archiveofourown.org/users/RicePoison/pseuds/RicePoison
Summary: Mermaid!AU, inspired by H2O/Mako Mermaids. Marinette and Co. sail out to sea on the Agreste yacht, bound for Miraculous Island! However their adventure is cut short by a series of incidents, someone wants them off the island. Will Marinette and Adrien, Nino, and Alya figure out what Miraculous Island is hiding? Or will they become lost in the sea mist?





	1. Chapter 1

**Author's Note:**

  * Inspired by [H2...No!](https://archiveofourown.org/external_works/419762) by RicePoison. 



> Alright, everyone! I'm here. I've decided to update my Miraculous/H2O "crossover" H2No! on AO3, including rewriting it a bit to be more... readable. Writing on the fly all the time with no clear direction on where you're headed? Yep, bad idea. That's why I'm going to make it a good idea and take my original story in a bit of a different direction, pairing it more with the H2O-style universe *squints at Mako Mermaids*, but within what is allowed in Miraculous. So, maybe Syren will come back? Oh! This time the characters will be... well, in character. 
> 
> Alright, we're about a year after the first rendition, let's start with a new version!

     The silence of a normally boisterous class was almost deafening as only pages were flipped through a geography textbook.  Through the text and pictures, Marinette Dupain-Cheng tapped her pencil on a specific image, reading the caption text to herself, thinking over her weekend plans. A slight rush came to her head as she remembered that this weekend in particular, her friends were going out to the exact island that was mentioned in her book.  _The moon pool, a key feature of Miraculous Island had laid undisturbed for years now. The cool water from the ocean rushed into the grotto, circling before it returned to where it came. In a volcanic caldera, it was hidden from the rest of the island, the only way to enter was from the ocean - or that’s what was known._ Marinette's heart fluttered as she imagined diving off the shore of the island and finding that exact cave. Maybe Adrien would- The class bell rang, however, she didn't hear it. Instead, she barely heard Alya ask her something. She heard Alya ask again, muffled… and again, clearer… 

    “Marinette! I need to know if you’re coming with us to the Island.” Alya abruptly tapped Marinette's textbook, waking her friend from her daydream. 

    “Oh right, that’s this weekend, right?” Marinette closed the book. Alya had arranged with Nino and Adrien that they’d head out the next morning. Placing the textbook inside her backpack, her head was still buzzing from her daydream. “Did we need to bring anything? Was it going to rain this weekend? I’ve got rain ponchos!” 

    “Don’t worry so much, Marinette. Adrien has everything we need on his father’s yacht.” Alya reassured her friend, getting up to leave, she waved at Nino and Adrien as she pulled Marinette from the classroom. “I’ll see you guys tomorrow morning, bright and early!” 

    Marinette shifted uncomfortably, realizing how early Alya was referring to, groaning at the thought of 6 am as her friend laughed. "How early should we be at the pier?" 

* * *

     The next morning, Adrien had been the first to arrive with Nino, his bodyguard towering over him like a massive… gorilla. Might be why they call him that, maybe. Marinette giggled at the resemblance as she rolled her small suitcase up behind her - containing most of her belongings. She noted that Nino had brought an excess of supplies, backpacks, a laptop, and bubble wands — for whatever reason was a mystery to Marinette. They waved her over as Gorilla stoically looked towards her. 

    Having just arrived, a moment behind Marinette, Alya nudged her friend's shoulder. “You’re staring again.” 

    “I can’t help it, Alya! Three days on an island with…Adrien.” Her friend raised an eyebrow at the blush covered Marinette's face as she swooned, then shaking her head as both of them walked forwards. “I forgot to ask, how far away from the pier is this island?"

    “Girl, have you been paying any attention in Geography class? We’re going to Miraculous Island!” Alya smirked, the small smile then spreading into a wide grin. Marinette noted the expression was almost fox-like “It’s not only the most mysterious island, but it’s got an amazing beach!”  

    “I didn’t pack my swimsuit!” the thought hadn’t crossed Marinette’s mind until now. she frantically looked to Alya as her friend laughed again. “I guess I can borrow one of yours…?” 

    “C’mon guys! We want to get out there before Lunch, right?” Nino motioned to the yacht, Adrien and Gorilla had already begun to climb aboard the three-storey vessel. “You brought the croissants, right Marinette?”  

    “That’s the one thing she didn’t forget,” Alya answered for her, pulling Marinette along to the boat. 

* * *

**[2 hours later… because being on a boat takes a long time if you’re crossing an ocean]**

    “Land Ho!” Nino called, somehow Gorilla had allowed him the ‘responsibility’ to use the ship’s intercom system. Marinette shook her head out of a sleepy haze, having fallen asleep in one of the deck chairs, she looked around to get orientated again. Standing upright, she walked to the railing, looking over to the sea below. They had anchored further out due to their boat’s size, so they were further from land than Marinette had anticipated.  

    “How are we going to get over there?” Alya had joined her, looking down at the water “I bet there are sharks this far out.” a clacking noise was heard from the left, Gorilla had begun to lower one of the attached lifeboats, motioning for the kids to come over. Alya left the railing, pulling Marinette’s bag with her “Stop your daydreaming and come on!” 

    Marinette stopped, then running over to Alya. Adrien had already helped Nino into the lifeboat, Alya decided once Adrien extended his hand to her that she didn’t need help - hopping into the boat with a fox-like grin on her face. Adrien looked at her before smiling at Marinette, his hand extended to help her into the boat. “I-I… why don’t you go first?”  

    “I should help you since I invited you.” Adrien was quick to grab her hand and help her over the gap. Her heart fluttered, and she looked down for a quick second to cover her flushed face. Seeing the opening between the yacht and the lifeboat, a drop to the ocean that was probably teeming with sharks! In her brief moment of panic, she jumped in, tripping over her own suitcase and she would’ve gone further if Alya hadn’t of grabbed her. 

    “Careful, what are we going to do with you if you fall in the ocean?” Alya chuckled, helping her friend sit down as she also helped Adrien get into the boat. A quick motion to Gorilla and the lifeboat was lowered to the water. “Besides, our Geography textbook said that it's too cold for sharks here.”

    “ALYA!” Marinette shot a look towards Alya as she laughed again. “Next time tell me if there are actually sharks in the water.”

    Alya nodded, smiling widely as she waved at Gorilla as the boat anchored itself for the evening, he didn't wave back, just staring at them. “I have a feeling that this is going to be a fun weekend!” 


	2. Chapter 2

**Notes for the Chapter:**

> Well, Chapter 2. I haven't touched this since November 3rd, 2017, so, let us continue this weird adventure.

     Sparkling white sand, contrasted with the deep green jungle beyond, and the extinct volcanic structure in the distance — Alya was not the only one taking in notes about this island. As Adrien and Nino pulled them to shore, Marinette hopped over the side of the boat, ankle deep in frigid ocean water, she ignored the initial shock of the cold water, walking on shore as the sand squished between her toes.

    “It’s weird this island is relatively uninhabited, it seems like a cool place!” Nino rummaged through the boat’s contents and slung his backpack over his shoulder, Marinette’s much-less practical rolling suitcase in his other hand. “The established campsite is a bit in from here, near the river. I’ll go ahead and find the path.” he went to venture on ahead, although only a short few meters in front of the rest of them. 

    “Wait, where’s my bag?” Marinette looked in the lifeboat, having not noticed if the others had taken it or not. 

    “I’ve got it!” Nino exclaimed, waving for them to come over “The trail is here, let’s go!” 

* * *

**[A little while later - a lot of walking may have involved, actually, it was a lot of walking]**

     Sitting on a large grey stone in the middle of the clearing, Alya looked annoyedly at Nino. “You said you knew the way, I’m quite sure I’ve seen this rock more than once” 

    “We’re here now.” Adrien sheepishly smiled, sitting down across from her. “All we have left is to set up the tent — luckily my father lent us the new tents from his line!”  He reached for and opened the backpack nearest to him, a collapsed round disc of purple fabric was nestled safely inside. With a swift flick of his wrist, the disk popped out into one small tent, enough for Alya and Marinette, then the second one for him and Nino. 

    Alya examined the purple patterned fabric, then pointed out the Agreste crest emblazoned throughout the pattern. “What’s your dad’s thing with butterflies?” 

    “It’s his logo. He has to include it in anything he produces, somehow. Besides, we can appreciate he actually contributed … well, it might’ve been mostly Nathalie… but its the thought that counts, right?” Adrien’s shoulders raised as he got up, looking back at the tents. “I’m gonna… go for a walk.” he turned on his heel, walking down one of the better-trodden paths through the jungle. 

    “Shouldn’t we try to stop him?” Marinette tried to voice her concern, however, Alya shook her head. 

    “The boy needs some alone time. He’ll come back when he’s ready.” 

* * *

     The undergrowth pulled at his heels, however, he continued through the dense jungle until he reached a rocky outcrop by the river. Adrien turned, walking onto the damp stones as he muttered to himself, trying to think of something other than the butterfly-clad tents that Nathalie had obviously arranged in place of his father. Upon pausing, then turning, he lost his footing, slipping on the algae-coated river stones. The rest happened too fast for his liking - one moment he was up in broad daylight, the next, he was slipping down a narrow passage, depositing him onto a bed of soft sand. “What—” he got up slowly, making sure he hadn’t been injured during the fall. “—is this place?” 

    A sparkling grotto before him, white sand beneath his feet, something about it looked so… preserved. He walked forwards, looking into the water. It looked like it went all the way through to the ocean, perhaps? He didn’t want to take any chances, nor did he want to be stuck down here. No one would find him, his father probably wouldn’t look for him. Adrien gazed at the rocky wall behind the pool, a purple shard of light catching his eye — a butterfly? He breathed, watching the black insect lift its wings and fly towards him, encouraging him to move. 

    “I’m sick of butterflies!” he made a split-second decision and dove into the pool, avoiding the butterfly landing on him. The frigid water a shock to him, he kicked further, knocking his shoulders against the bottom of the pool. Adrien opened his eyes, looking up at a coral as he tried to get orientated. There was something on the coral, but he needed air — fast. Emerging for a breath, he watched as the butterfly circled the pool, not taking notice of Adrien yet as he dove again, grabbing at the object on the coral. He looked down again, trying to swim to the ocean exit, but then deciding against it. Upon emerging, he held in his hand what he had grabbed. A black shell covered in intricate red designs, remarkable as sea water would usually wash away any paint. Prying it open, a single silver ring sat atop a small cushion of seaweed.

    “What’s this doing here?” he pocketed the shell and slid the ring onto his finger, starting to pull himself out of the water. The butterfly landed in front of him, just as he began to pull himself up. “Does it take a _cataclysm_  for you to go away?” the ring sparked with a bright green glow, the butterfly burning away in front of him. Adrien… well, he didn’t know what to think, instantly recoiling in surprise, and letting go of the side of the pool. “What was that?” 

* * *

  **[Back at the Campsite, nearing 10:30 pm]**

    “I think we should go check on Adrien. It’s been a while, maybe he’s hurt?” Marinette had been worried the entire time, vocalizing her concern to Alya and Nino. Nino looked up from the campfire kraft dinner he was making for all of them, shrugging to Marinette as he stirred the pot. “Fine. If you guys aren’t going to do it, I’ll go look for him!”

    “Ooh, while you’re gone, can you get some pics of the solstice moon?” Alya ran over to Marinette, handing her the pocket camera she had packed in her backpack. “You’d probably get a good vantage point to look for Adrien from the side of the mountain!” there seemed to be no concern in her voice, probably because the island was known for camping and no incidents had occurred. 

     _Yet_ … it echoed in Marinette’s mind that something might go wrong. She put the camera in her pocket. “I will be back within an hour.” 

* * *

Although the thought of going alone through the jungle scared Marinette, she followed a path along a stream. Seeing nothing, she started to climb a small rock outcropping by the mountain, flitting her phone flashlight in every spot she thought Adrien might be. “He couldn’t of gotten far, the island is smaller than Paris.” She cast a look on the outcrop, sighing before scaling the volcano.

 

 


	3. Chapter 3

**Notes for the Chapter:**

> Alright, if you were following the previous version of this story, from this chapter onwards is thus going to begin the changes I've added to my original storyline. More looking at the timing for transformations, and editing how early our heroes discover their powers. While my previous iteration had Adrien discovering right away that he's in an extended fishy situation, this one I've taken a bit more of a route towards the first episode of Mako Mermaids. Without further ado, chapter 3.

    It must’ve been nearing midnight, Marinette was almost halfway up the volcano when she looked around. The moon was almost directly over the volcano, causing all the rocks around Marinette to illuminate in silver light — something caught her eye a few feet down from her, a purple glow among the silver moonlight. Marinette turned, to slide down the exposed basalt stone, which was quite damp — despite it having not rained yet. She brought her phone up as she looked for the bright glow again, shutting it off once she established that it was a cave, with a light source inside? I should get Alya and Nino. She was about to turn on her heels and head back. But what if Adrien is in there? Marinette took a step in, walking towards the faintest purple glow of another corridor in front of her. “Hello? Adrien?” 

    A rustle stopped her, she turned around to find the entry she had passed through to be gone. That… can’t be! Am I trapped in here? Panicked, she felt for the door, but instead, a cool stone wall was in its place. She turned again, inhaling shakily as she walked again towards the light. To her surprise, even though the stones were cold, the air was warm — as if someone had been there prior to her. She hoped it was Adrien as she turned the corner, revealing a whole room illuminated in purple light. “Adrien?”

    “How’d you get in here?” 

    Marinette froze. That wasn’t Adrien. She raised her head to see the face of a masked man, shaking, she took a step back. _Where’s Adrien? Who is this man? Why is he in here? How am I getting out of here?_  She yelped as the ground seemingly started to give under her feet, eyes wildly flashing towards the man as he raised his arms.

    “Begone!” a flash, several white butterflies extended from the man’s form, turning from violet to black as the started to swarm above his head, then towards her. She ducked, unfortunately, the motion causing her to become further pulled into the floor. “Get out!” was the last shout she heard before being pulled completely into the quicksand that quickly surrounded her body. 

* * *

**[Just under the chamber, in the grotto** ]

    Adrien had given up on scaling the wall to get back to the tunnel. He sighed, sitting back down at the edge of the pool - even if someone had been looking for him, if they came down into the grotto, they’d be stuck as well. He gazed up, watching the moon start to crest over the top of the volcano, bathing him in silver light, hearing a distinct sound of water bubbling. Adrien quickly redirected his gaze to the pool, the water bubbling in reaction to the moon’s light. Another sound, he looked up once more to see a purple glow in the wall above the pool, a tunnel appearing as someone quickly shot out. He instantly recognized her bluish hair, him panicking as she hit her head on the side of the pool and slipped under the bubbling water. 

    “Marinette!” Adrien’s first instinct kicked in, diving into the pool after her. He pulled his hands around her torso and swam back to the surface, looking up at the moon as it finally illuminated the whole grotto. He looked back at Marinette, who was out cold from the blow to her head. “Marinette, wake up!” He could barely hear himself think as the bubbling water raged around him, he stopped as e couldn’t feel his lower half. Maybe the pool was volcanic? Maybe it had burned his legs off? He couldn’t see anything in the water, still trying to tread to keep Marinette’s head above the bubbles. Then as suddenly as it began, the moon started to move away from the top of the crater, the bubbles suddenly ceased. 

    Adrien looked down at his friend, and then further down. His eyes widened seeing a pink fish-like tail extending from her torso, almost letting her go out of shock. N _o, this isn’t the time for this, Agreste! Get her out of the water!_ Adrien pushed his weight up from the side of the pool, lifting Marinette back onto the white sand before attempting to get a leg up on the side of the pool. He almost fell backwards, seeing his legs — well not his legs, he found his own green coloured tail extending in front where his hips where. _What’s going on?_ He looked around, trying to find something to answer his questions before pulling himself together. He pulled himself up on the sand, then shimmying his way over to his friend. 

    “This can’t be happening, Marinette, wake up.” He dipped his head to her mouth, attempting to perform CPR, as it was the only thing on his mind to help her come back. He paused between his compressions, listening for her breath, then trying again. On his third try, she coughed a mouthful of water out, Adrien putting an arm around her back as he lifted her to an upright position. She hadn’t opened her eyes yet, which was when Adrien realized — they were both still in a _fishy_  situation. He could’ve laughed at that pun but instead brought her back to the side of the pool. “She can’t see me like this. I should get out of here." He slipped once again into the water, making a quiet exit out the ocean exit of the pool as Marinette finally came to.   


   “A-Adrien…?”

    “He’s safe, rest up. You hit your head pretty hard.” Marinette propped herself up, looking down into the pool. Peering further she saw the source of the voice, a green sea turtle, it's back intricately painted with red. 

    “Who—“ Marinette held her head, then looking back at her own tail. “What happened to me?!” 

    “I’m not sure what happened to you. However, I can give you something that can help you." The turtle swam to the corner of the pool, ignoring Marinette's initial panic at her new form. "I am Master Fu, and this grotto is my home. I'm sure you've travelled a long way to come here. If you wait long enough, your scales will dry off." 

    Marinette stopped for a minute, thinking to herself as the turtle made his way up to the sand beside her. "I'm talking to a turtle, this is not crazy at all, right?" She eyed the reptile as he placed a black shell he had been carrying on his back to her. She took it carefully, opening it, looking down at the earrings that were carefully laid upon a small bed of kelp. "What are these?"

     "Marinette Dupain-Cheng, I present you with the miraculous of the Ladybug, with this you can harness the powers of creation." The turtle slipped back into the pool, looking back at her as she affixed the earrings to her ears. "We'll meet again, soon." 

     "Wait, how do I get out of here?" Marinette watched as he sunk under the blue water of the moon pool, where she assumed led out to the ocean. She sat back, sparkles beginning to fly off her tail, leaving her once again with legs. She pinched herself, hoping to wake herself from this odd dream, but found she was wide awake. She looked around again for an exit on the land, and upon finding none, she eyed the moon pool itself. If that was the way that the turtle left, it was probably the only way out. Walking to the edge of the pool, she dipped a hand in and took it out. No fishtail? Confused, she looked at her legs. Maybe she was actually stuck here? Marinette was about to turn around and look for a land exit when she lost her balance, falling backwards into the pool. Reorientating herself, she looked at the ocean exit, kicking rapidly to leave the pool. 

     Adrien had already pulled himself onto shore and began to dry off when he saw Marinette emerge from the waves. He carefully watched as she swam to the shore and pulled herself up onto the rocks, waiting for her to transform back to her human form. If there was one thing he knew now, it was how suspicious Alya and Nino would be when they returned to the camp. Shuddering at the thought of Alya bombarding him with questions, he turned, dissapearing into the dense treeline. 


End file.
